I'm pretty sure that means you apply through AAMC as with any other school (the primary application) and send the letters to the school itself. There should be some section on the school's website (FAQs or something) that should tell you where the letters are to be sent.
You can use a third-party delivery service, such as Interfolio, to get letters to that school. As there are only 20 schools participating in the pilot program, I wouldn't be surprised if more than one of the schools you're applying to aren't participating.
